Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755684AbdLGNNI (ORCPT ); Thu, 7 Dec 2017 08:13:08 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:34734 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755667AbdLGNNF (ORCPT ); Thu, 7 Dec 2017 08:13:05 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Aaron Sierra , Sasha Levin Subject: [PATCH 4.14 38/75] serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X Date: Thu, 7 Dec 2017 14:08:00 +0100 Message-Id: <20171207130820.315285173@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171207130818.742746317@linuxfoundation.org> References: <20171207130818.742746317@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1354 Lines: 38 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Aaron Sierra [ Upstream commit 0ab84da2e076948c49d36197ee7d254125c53eab ] The upper four bits of the XR17V35x fractional divisor register (DLD) control general chip function (RS-485 direction pin polarity, multidrop mode, XON/XOFF parity check, and fast IR mode). Don't allow these bits to be clobbered when setting the baudrate. Signed-off-by: Aaron Sierra Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_port.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2586,8 +2586,11 @@ static void serial8250_set_divisor(struc serial_dl_write(up, quot); /* XR17V35x UARTs have an extra fractional divisor register (DLD) */ - if (up->port.type == PORT_XR17V35X) + if (up->port.type == PORT_XR17V35X) { + /* Preserve bits not related to baudrate; DLD[7:4]. */ + quot_frac |= serial_port_in(port, 0x2) & 0xf0; serial_port_out(port, 0x2, quot_frac); + } } static unsigned int serial8250_get_baud_rate(struct uart_port *port,